This application is based upon and claims the benefit of priority of Japanese Patent Applications No. 2001-108877 filed on Apr. 6, 2001 and No. 2001-328982 filed on Oct. 26, 2001, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a wiper arm having a rotation restriction member that prevents at user""s choice an arm member pivotally connected to an arm head from rotating to a position where the arm member rests in place at a given angle to the arm head in a direction away from a windshield glass (in a lock back state).
2. Description of Related Art
A conventional wiper arm has an arm head fixed to a pivot shaft, an arm member hinged on a holding pin attached to the arm head so as to rotate by a given angle in a direction away from a windshield glass and a spring bridging between the arm head and the arm member for biasing the arm member toward the windshield glass so that a blade rubber of a wiper blade held by the arm member is pressed against the windshield glass.
It is well known to rotate the arm member by the given angle to the arm head in a direction away from the windshield glass and to make the arm member rest at a position where an end of the arm member comes in contact with the arm head, while the arm member is urged against the arm head by a biasing force of the spring. That is, the wiper arm is in a lock back state.
Further, JP-A-63-30261 proposes a wiper arm construction in which an arm member is held in a semi-lock state. This construction is applicable to a vehicle in which, when the arm member is rotated relative to the arm head, a base end portion of the arm member interferes with a periphery of an engine hood so that it is impossible to turn to the lock back state. According to JP-A-63-30261, after the arm member is rotated by a relatively small angle to the arm head in a direction away from the windshield glass, a spacer mounted in the wiper arm is moved manually so as to interpose itself between the arm member and the arm head. Accordingly, the spacer prevents a return rotation of the arm member due to a biasing force of a spring in a direction closer to the windshield glass. That is, the arm member rests in the semi-lock back state.
Recently, a wiper arm made of resin has been applied to the vehicle, in particular, to a rear windshield glass in view of more attractive appearance and lighter weight. Generally, this kind of wiper arm has a feature of enabling the lock back state for a purpose of maintenance such as a replacement of a blade rubber, unless the vehicle body has a limitation on realizing the same.
However, the conventional wiper arm constructed for enabling the lock back state has a drawback that, if an outside force more than the spring biasing force urging the arm member toward the windshield glass acts on the arm member in a direction away from the windshield glass, the arm member is brought into the lock back state. For example, when the vehicle is washed with a car washer, a washer tool such as a mop and a brush may cling accidentally to the arm member and turn the arm member to the lock back state. The washing operation, if continued in the lock back state, is prone to cause the wiper arm to be damaged.
On the other hand, there is known a wiper arm in which an arm member is pivotally connected to an arm head but can neither rest in the lock back state nor rest in the semi-lock back state. That is, though the arm member can be rotated in a direction away from the windshield glass, the arm member returns to an original position due to a spring biasing force unless continuously held by hand. This construction gives the user an inconvenience on performing the maintenance mentioned above.
An object of the invention is to provide a wiper arm in which a user can switch over at choice from a first operation mode that prohibits the arm member from moving to the lock back state to a second operation mode that allows an arm member to move to and rest in the lock back state. Accordingly, if the user selects the second operation mode and moves manually the arm member to the lock back state, a maintenance is easily performed and, if the user selects the first operation mode, a damage of the wiper arm due to an accidental movement of the arm member to the lock back state is avoided.
To achieve the above object, in a wiper arm having an arm head whose end is to be fixed to a pivot shaft and whose the other end has a holding axis, an arm member whose end is pivotally connected to the arm head so as to rotate about the holding axis in a direction away from the windshield glass and whose the other end is to be connected with a wiper blade, and a biasing member bridging between and retained by the arm head and the arm member for biasing the arm member toward the windshield glass so that the wiper blade may be pressed against the windshield glass, the biasing member is so operative that the arm member rests at a position where the arm member comes in contact with the arm head, when the arm member is rotated beyond a given angle to the arm head in the direction away from the windshield glass, and returns to an original position, when the arm member is rotated within the given angle to the arm head in the direction away from the windshield glass.
In the wiper arm mentioned above, a rotation restriction member is attached to at least one of the arm head and the arm member so that a position of the rotation restriction member relative thereto is changed over at user""s choice from a first position, where the rotation restriction member restricts the arm member to the rotation only within the given angle to the arm head, to a second position, where the rotation restriction member allows the rotation of the arm member beyond the given angle to the arm head.
If the user selects the first position, when the vehicle is washed with a car washer, a possible damage of the wiper arm due to a washer tool such as a mop and a brush, which may cling accidentally to the arm member and turn the arm member to the lock back state, is avoided.
On the other hand, if the user selects the second position, the arm member is manually rotated to the lock back state, when necessary, so that a blade rubber or an arm blade replacement operation for a maintenance purpose is easy or the blade rubber deformation or freezing is prevented.
Preferably, the rotation restriction member is a head cover detachably attached to the arm head. The head cover has a stopper wall that comes in contact with the arm member, when the arm member is rotated relative to the arm head in the direction away from the windshield glass. Accordingly, the change from the first position to the second position is executed by detaching the head cover from the arm head so that the stopper wall does not come in contact with the arm member.
As an alternative, the rotation restriction member is a head cover whose end is pivotally connected to an end of the arm head. The head cover has as topper wall that comes in contact with the arm member, when the arm member is rotated relative to the arm head in the direction away from the windshield glass. Accordingly, the change from the first position to the second position is executed by changing an inclination angle of the head cover to the arm head so that the stopper wall does not come in contact with the arm member.
It is preferable that the stopper wall, which protrudes inward from an end of the head cover, is inserted into a gap between the arm head and the arm member at the first position and does not exist in the gap at the second position.
As another alternative, the rotation restriction member is a cap rotatably attached to a fastener by which the arm head is to be fixed to the pivot shaft. The cap covers the fastener and has a stopper surface that interferes with the arm member, when the arm member is rotated relative to the arm head in the direction away from the windshield glass. Accordingly, the change from the first position to the second position is executed by changing the angular phase of the cap relative to the fastener so that the stopper surface does not interfere with the arm member.
It is preferable that the cap is provided at a circumference thereof with the stopper surface having a notch and, at the second position, the notch is oriented to face the end of the arm member or with a protruding portion that constitutes the stopper surface and, at the first position, the protruding portion is orientated to face the end of the arm member.
As further alternative, the rotation restriction member is a head cover whose one portion is pivotally connected to the arm member and whose the other portion is engaged with the arm head. The head cover has an end periphery that interferes with the arm member, when the arm member is rotated relative to the arm head in the direction away from the windshield glass. Accordingly, the change from the first position to the second position is executed by releasing the engagement of the head cover with the arm head and rotating the head cover hinged on the arm member so that the end periphery of the head cover does not interfere with the arm member.